class_docstr: Reads a TransformFn written by WriteTransformFn.
class_docstr_tok: ["Reads","a","TransformFn","written","by","WriteTransformFn","."]
code: def expand(self, pvalue):
      transform_fn_path = os.path.join(
          self._path, tft.TFTransformOutput.TRANSFORM_FN_DIR
      )
      saved_model_dir_pcoll = (
          pvalue.pipeline
          | "CreateTransformFnPath" >> beam.Create([transform_fn_path])
      )
  
      metadata = metadata_io.read_metadata(
          os.path.join(
              self._path, tft.TFTransformOutput.TRANSFORMED_METADATA_DIR
          )
      )
  
      return saved_model_dir_pcoll, metadata
  
file_path: transform/tensorflow_transform/beam/tft_beam_io/transform_fn_io.py
imports: import os
  import apache_beam
  import tensorflow_transform
  from tensorflow_transform import impl_helper
  from tensorflow_transform.beam import common
  from tensorflow_transform.beam.tft_beam_io import beam_metadata_io
  from tensorflow_transform.tf_metadata import metadata_io
label_desc: Use image node_id 2 for calling the ReadTransformFn obj's underlying member method code with example usage: obj.expand(pvalue) and returns: saved_model_dir_pcoll,  metadata